1. Field of the Invention
This invention relates in general to walking beam pump jacks and more particularly to walking beam pump jacks for use in oil well pumping and the like.
2. Description of the Prior Art
At the present time there are several types of pumps which are used for pumping liquids from oil and gas wells. These pumps include walking beam pump jacks, hydraulic rod-lifting pumps and down-hole hydraulic pumps. The down-hole hydraulic pumps operate by pumping a motive fluid through a conduit down into a well. The hydraulic fluid drives the mechanism of an elongated pump which resides at a desired depth of the well. Well fluids and the hydraulic fluid are conveyed to the surface in a conduit or conduits separate from that which conveys the hydraulic fluid down to the pump. These down-hole hydraulic pumps are generally used for short term pumping at remote locations.
Another type of pump which has been used for short term, remote location pumping is the hydraulic, rod-lifting pump. These pumps reciprocate a pumping rod, often called a sucker rod, which extends through the well bore from the surface to a desired depth. Attached to the bottom of the sucker rod is a one way valve which lifts liquid on the upstroke and gathers more liquid for lifting on the downstroke. The hydraulic lifter at the surface comprises a horizontally journalled pulley over which a cable extends. The ends of the pulley are connected to hydraulic cylinders which can raise and lower the pulley along a vertical frame. One end of the cable is fixed and the other is attached to the sucker rod so that as the pulley is raised and lowered, the sucker rod is raised and lowered as well.
The hydraulic rod-lifting pump has been made portable by mounting the vertical pulley frame, hydraulic cylinders, and hydraulic pumps on a trailer which can be a towed to a well location. The vertical pulley frame has been pivotally attached so that it can be laid down during transportation. However, heavy pumping loads on the hydraulic cylinders has made these devices short lived. Also, this method of pumping is not as rapid or as efficient as presently available walking beam pump jacks. Accordingly, it has only been used for temporary, remote location pumping.
Walking beam pump jacks are generally used only for longer term pumping at wells which are more accessible. This is because the walking beam pump jacks have heretofore been not easily transported and are more or less permanently affixed to a well location when they are used.
Walking beam pump jacks operate by reciprocating a sucker rod which extends from the surface through a well bore to a one way valve. Reciprocation of the sucker rod pumps liquids in the same manner as the reciprocation of the sucker rod in a hydraulic rod-lifting pump.
The walking beam pump jacks in present use obtain a significant advantage over other pumps by use of a fixed-mount, long-stroke walking beam driven by a counterweighted rotating drive. The walking beam is mounted on a relatively tall support. An assembly for attaching the sucker rod to the walking beam is disposed at one end of the walking beam. Attached to the other end of the walking beam and extending downwardly is a drive yoke which extends from the walking beam to a pair of counterweighted drive arms. These drive arms rotate about an axis at one end of the arms. A diesel or propane engine drives the arms to rotate which, in turn, rocks the walking beam as a result of the motion of the yoke.
The walking beam must be mounted in a relatively high position because there must be room for the yoke and drive arms to extend and rotate beneath one end of the walking beam. The drive arms must be relatively long and counterweighted by a relatively heavy counterweight in order to produce a proper reciprocating stroke of the sucker rods and in order to lift the relatively large weight of the sucker rod string. Because of this relatively large height, conventional walking beam pump jacks can not be transported over most highways. Bridges and other obstructions prevent the transportation of devices as tall as a conventional walking beam pump jack. Moreover, the heavy equipment and frame components have prevented easy transportation of these type of pumps. Therefore, walking beam pump jacks have only been used for long term pumping and the pumps have been assembled at the well cite on more or less permanent foundations.
While walking beam pump jacks are the preferred devices for pumping from most deep wells and oil wells, it has been impossible or uneconomical to use such pumps for short periods or in remote locations. This is because these pumps must be assembled at the well location and are relatively difficult to move.